Drilled and integrated secondary fuel nozzle and manufacturing method

Abstract

A secondary fuel nozzle is formed by brazing and welding a central core, a cylindrical body, and a unitary secondary fuel nozzle portion. The central core has a central bore for receiving a liquid fuel cartridge, and at least two passages concentric with the central bore. The secondary fuel nozzle portion includes a base flange and a main shaft having a central bore for aligning with the central bore of the core and for receiving the liquid fuel cartridge, and a plurality of peripheral bores disposed at spaced locations about the central bore for flow communication with the concentric passages of the core. The core is brazed to the base flange and the cylindrical body is disposed around the core and welded to the base flange to define a one-piece secondary fuel nozzle assembly.

1. A method of manufacturing a secondary fuel nozzle, comprising:
 providing a core portion having proximal and distal longitudinal ends, a central bore extending therethrough from said proximal end to said distal end for receiving a liquid fuel cartridge, and at least two passages concentric with said central bore and extending axially in parallel to said central bore along at least a part of the length thereof to said distal end; 
 providing a unitary secondary fuel nozzle portion including a base flange, and a main shaft having a central bore for aligning with the central bore of the core and for receiving the liquid fuel cartridge; 
 gun drilling a plurality of peripheral, axially extending bores so that each bore is disposed at a respective circumferentially spaced location about and extending in parallel to the central bore of the secondary fuel nozzle portion for flow communication at a proximal end thereof with at least one of said concentric passages of the core portion at the distal end of the core portion; and 
 at least one of brazing and welding said core portion to said base flange of said unitary secondary fuel nozzle portion, whereby the core portion and nozzle portion are integrated to define a one-piece secondary fuel nozzle assembly. 
 
     
     
       2. A method as in  claim 1 , wherein providing a core portion comprises providing a unitary core member having said central bore and concentric passages and providing a cylindrical body section in surrounding relation to said core member. 
     
     
       3. A method as in  claim 2 , wherein at least one of brazing and welding said core portion to said base flange comprises interposing a braze plate between a distal end face of the core member and the base flange of the nozzle portion;
 heating to fuse the core member and base flange together; and 
 circular welding the cylindrical body section to the base flange. 
 
     
     
       4. A method as in  claim 2 , wherein said concentric passages are machined in said core member. 
     
     
       5. A method as in  claim 1 , wherein a radially inner one of two adjacent said concentric passages is longer than the other so as to extend further than the other towards said proximal end of the core, and further comprising drilling an access hole radially to the extended portion of said radially inner concentric passage. 
     
     
       6. A method as in  claim 1 , wherein an access hole is drilled to extend radially from an outer peripheral surface of said core portion to the central bore thereof. 
     
     
       7. A method as in  claim 1 , further comprising forming at least one of bores and slots adjacent to or at an outer peripheral surface of the core portion for bolt access for attachment to a combustion end cover, and forming a plurality of holes in the base flange for respectively aligning with the bolt bores or slots of the core. 
     
     
       8. A method as in  claim 2 , further comprising forming slots in an outer peripheral surface of the core member for bolt access for attachment to a combustion end cover, and forming a plurality of holes in the base flange for respectively aligning with the bolt slots of the core member. 
     
     
       9. A method as in  claim 1 , wherein a plurality of fins project from and extend along at least a portion of the length of the main shaft, and wherein said gun drilling comprises gun drilling a first set of said peripheral bores in the main shaft to surround said central bore thereof, and gun drilling a second set of said peripheral bores so that at least one extends axially through each said fin.